Intravenous drug use is a major vector of HIV transmission. Contingency management, a behavioral treatment in which participants earn reinforcers for drug abstinence, has been shown to reduce the use of illicit drugs and to be an effective treatment of drug dependence. Pharmacological treatment, such as opioid agonist maintenance, can reduce use of heroin and other opiates. We are conducting clinical trials of behavioral and pharmacological treatments designed to reduce drug use and other HIV-risk behaviors in individuals who are polydrug dependent. Participants complete the HIV-Risk Taking Behaviour Scale (HRBS) in written questionnaire form during the studies. Drug use is monitored in structured interviews and by drug screens on frequently collected biological matrices.